Today I found that on ISP “tiera” they started to block tcp inside 6in4 tunnels making them mostly useless for any purpose. icmp and udp are not filtered.
It’s TSPU equipped ISP. Likely others are affected. ISPs without TSPU are OK.
They broke entire 6in4 tunnel technology, including 6to4 and tunnelbroker.net
NOTE. They are likely reading this. Care what you write, do not give them more ideas they can use